NEHA Environmental Health and Safety (EHS) Practice Exam

The property that makes a waste reactive is its ability to generate toxic fumes when heated. Reactive wastes can undergo violent chemical reactions, which might lead to explosions, the release of toxic gases, or other hazardous situations when they are exposed to heat, pressure, or moisture. This characteristic poses significant risks during storage and disposal, as the potential for dangerous reactions can lead to environmental contamination and pose risks to human health.

In contrast, safely disposing of waste does not define a reactivity characteristic, while having no effect on the environment suggests a lack of harmful properties, which is contrary to being classified as reactive. The ability to be used as a fertilizer indicates that a substance might be beneficial and non-hazardous, further distinguishing it from reactive wastes. Thus, the generation of toxic fumes when heated is a clear indicator of the reactivity of certain waste materials.